One Way and Round Trip Delays Using Telephony In-Band Tones

Abstract

There is disclosed a method for measuring the delay between a source device and a destination device on a network. The source device may generate a timestamp and encode the generated timestamp as an in-band tone sequence. The source device may transmit the in-band tone sequence to the destination device. There is also disclosed a network device comprising a timer to generate a timestamp, a tone generator capable of encoding the timestamp as an in-band tone sequence and a tone transmitter to transmit the in-band tone sequence.

1 . A method for measuring delay between a source device and a destination device on a network comprising:
 the source device generating a timestamp   the source device encoding the generated timestamp as an in-band tone sequence   the source device transmitting the in-band tone sequence to the destination device.   
     
     
         2 . The method of  claim 1  further comprising
 the destination device receiving the in-band tone sequence and 
 the destination device decoding the in-band tone sequence to retrieve the generated timestamp. 
 
     
     
         3 . The method of  claim 2  further comprising
 the destination device generating a detection timestamp of when the in-band tone sequence was received by the destination device. 
 the destination device storing the detection timestamp. 
 
     
     
         4 . The method of  claim 3  further comprising
 the destination device encoding the detection timestamp as a second in-band tone sequence 
 the destination device transmitting the second in-band tone sequence to the source device. 
 
     
     
         5 . The method of  claim 4  further comprising
 the source device receiving the second in-band tone sequence 
 the source device decoding the second in-band tone sequence to retrieve the detection timestamp. 
 
     
     
         6 . The method of  claim 5  further comprising
 the source device calculating the delay between it and the destination device using the generated timestamp of the source device and the detection timestamp of the destination device. 
 
     
     
         7 . The method of  claim 1  wherein the generation timestamp is encoded as DTMF tones. 
     
     
         8 . The method of  claim 1  wherein the generation timestamp is encoded as custom defined tones. 
     
     
         9 . The method of  claim 1  wherein the source device and destination device are devices on a circuit-switched network. 
     
     
         10 . The method of  claim 1  wherein the source device and destination device are devices on a packet-switched network. 
     
     
         11 . The method of  claim 1  wherein the source device is a device on a circuit-switched network and the destination device is a device on a packet-switched network. 
     
     
         12 . The method of  claim 1  wherein the source device is a device on a packet-switched network and the destination device is a device on a circuit-switched network. 
     
     
         13 . The method of  claim 1  further comprising synchronizing a source timer in the source device with a destination timer in the destination device before the source device transmits the in-band tone sequence. 
     
     
         14 . A network device comprising
 a timer to generate a timestamp   a tone generator capable of encoding the timestamp as an in-band tone sequence   a tone transmitter to transmit the in-band tone sequence.   
     
     
         15 . The network device of  claim 14  further comprising
 a memory to store the timestamp 
 a tone receiver to receive a second in-band tone sequence and 
 a tone detector to decode the second in-band tone sequence. 
 
     
     
         16 . The network device of  claim 15  wherein the timestamp is encoded as DTMF tones. 
     
     
         17 . The network device of  claim 15  wherein the timestamp is encoded as custom defined tones. 
     
     
         18 . A system for measuring delay between a source device and a destination device on a network comprising:
 the source device comprising
 a timer to generate a timestamp 
 a tone generate to encode the generated timestamp as an in-band tone sequence 
 a tone transmitter to transmit the in-band tone sequence the destination device comprising 
 a tone receiver to receive the in-band tone sequence 
 a tone detector to decode the in-band tone sequence and retrieve the timestamp. 
   
     
     
         19 . The system of  claim 17  wherein the source device is a device on a circuit-switched network and the destination device is a device on a packet-switched network. 
     
     
         20 . The system of  claim 17  wherein the source device is a device on a packet-switched network and the destination device is a device on a circuit-switched network. 
     
     
         21 . The system of  claim 17  wherein the timestamp is encoded as DTMF tones. 
     
     
         22 . The system of  claim 17  wherein the timestamp is encoded as custom defined tones.